Tham khảo tài liệu 'composite materials design and applications part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Figure Practical Determination of a Laminate Subject to Membrane Loading Apparent Moduli of the Laminate Inversion of Equation above allows one to obtain what can be called as apparent moduli and coupling coefficients associated with the membrane behavior in the plane x y. These coefficients appear in the following relation e. Sox 1 Vyx xy Sox Ex Ey G xy e h A -1- V oy Vxy 1 Pmy Coy Ex Ey G xy g I oxy T oxy frill- 1 H 1H m Ey 1 1 G xy T oxy Consequence Practical Determination of a Laminate Subject to Membrane Loading Given The stress resultants are given and denoted as Nx N Tv. x y xy Using the values of these stress resultants one can estimate the ply proportions in the four Assume in Figure that the plies are identical same material and same thickness . The problem is to determine The apparent elastic moduli of the laminate and the associated coupling coefficients in order to estimate strains under loading The minimum thickness for the laminate in order to avoid rupture of one of the plies in the laminate See Section . 2003 by CRC Press LLC Principle of Calculation Apparent moduli of the laminate The matrix h A evaluated using Equation can be inverted and one obtains Equation as I . I - ox I I Ì eoy g Ó goxy J 1 Ex Vxy _ _ Ex __x Ex Vyx _ Ey 1 Ey m_ Ey hxy G xy mxy G xy 1 G xy Sox Ì Soy T oxy We have already determined the apparent moduli and the coupling coefficients of the laminate. Nonrupture of the laminate Let s st and T be the stresses in the orthotropic axes f t of one of the plies making up the laminate that is subjected to the loadings Nx Ny Txy. Let h be the thickness of the laminate unknown at the moment so that the rupture limit of the ply using the Hill-Tsai failure criterion is just reached. One then has for this ply8 _2 _2 _ _ _2 Ơ St ơ ơt T _ __ __ _ - 2 _2 2 _2 s St s Tt rupture rupture rupture rupture Multiplying the two parts of this equation with the square of .
